Heat exchanger capable of preventing heat stress

ABSTRACT

The object of the present invention is to provide a heat exchanger which can prevent the tubes from being damaged by the heat stress caused by the temperature difference between the reinforcement members and the tubes of the core portion.  
     A heat exchanger comprises a core portion having a plurality of tubes  12   a  and fins  12   b  which are arrange so as to be alternately laid in layers. In the core portion  12 , the tubes  12   a  are arranged at the outermost ends in the piling direction V of the tubes  12   a  and the fins  12   b  and the inserts ( 14 ) which reinforce the core portion  12  are fixed to the tubes ( 12   a ) and tanks ( 11, 13 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger and is effective whenapplied to a heat exchanger, such as a radiator, for cooling enginecooling water.

2. Description of the Related Art

A conventional radiator, as shown in FIG. 13 of the patent document 1,through which a cooling water flows, comprises: a core portion 12comprising a plurality of tubes 12 a disposed in layers in the Vdirection in FIG. 13, and fins 12 b arranged between the tubes 12 a; andtanks 11 connected to the ends of the tubes 12 a in a longitudinaldirection L thereof which tanks distribute and collect the cooling waterflowing through the tubes 12 a. In this configuration, the heat of thecooling water, having absorbed heat from an engine, etc. and flowingthrough the tubes 12 a in a high temperature state, is transmitted tothe fins 12 b and air flowing through the fins 12 b absorbs the heattransmitted to the fins 12 b. Due to this, the radiator can cool thecooling water.

Further, the radiator 50 disclosed in the patent document 1 comprises:tanks 11 at the both ends in the direction perpendicular to thelongitudinal direction L of the tubes 12 a, that is, in the direction Vin which the tubes 12 a and the fins 12 b are alternately laid inlayers; and inserts 14 fixed to the core portion 12 and for reinforcingthe core portion 12.

As a result, the core portion 12 is not damaged by a deformationthereof, such as torsion, caused by an external force. In addition, theradiator can attain its inherent role in which it cools the coolingwater flowing through the tubes 12 a.

[Patent Document 1]

Japanese Utility Model Publication No. 2-92491

On the other hand, the heat exchanger of the patent document 1 has astructure in which the inserts 14 are integrally fixed to the fins 12 bof the core portion 12, for reasons of manufacturing, in which, forexample, when the tubes 12 a and the fins 12 b are joined by brazing,the tubes 12 a and the fins 12 b can be easily pressed by the inserts14.

Due to this, there may be produced a temperature difference between theinsert 14 fixed to the fin 12 b cooled by a cooling air flow (wind) andthe tube 12 a through which a high temperature cooling water flows. Inthe worst case, the thermal stress produced by the temperaturedifference may destroy the thin tubes 12 a having thicknesses less thanthat of the insert 14.

In the radiator, a state in which there is no temperature differencebetween the insert 14 and the tubes 12 a when the engine is not inoperation and another state in which there is the temperature differencetherebetween are alternately repeated and, as a result, the tubes 12 amay be destroyed by the repeated stress.

SUMMARY OF THE INVENTION

The present invention has been developed with the above-mentionedproblems being taken into consideration, and the object thereof is toprovide a heat exchanger having a core portion, in which the tubes andthe fins are alternately laid in layers, and reinforcement members forreinforcing the core portion, wherein the tubes are prevented from beingdamaged due to the heat stress caused by the temperature differencebetween the reinforcement members and the tubes of the core portion.

In order to realize the above-mentioned object, in a first aspect of thepresent invention, there is provided with a heat exchanger having a coreportion in which tubes and fins are alternately arranged in layers andreinforcement members for reinforcing the core portion and characterizedin that in the core portion (12), the tubes (12 a) disposed in theoutermost sides in the piled direction (V) and the reinforcement members(14) are arranged so as to come into contact with each other.

In this configuration, the reinforcement members (14) are arranged so asto be in contact with the tubes (12 a) and, therefore the heat of thetubes (12 a) can be transmitted to the reinforcement members (14). Dueto this, compared to the case of the patent document 1 shown in FIG. 13,where the reinforcement member (14) and the fin (12 b) are arranged tobe in contact with each other, the temperature difference between thereinforcement members (14) and the tubes (12 a) can be made smaller.Therefore, a heat stress caused by the temperature difference isunlikely to be produced. As a result, it is possible to prevent thetubes (12 a) from being damaged due to the heat stress.

According to a second aspect, in the heat exchanger disclosed in thefirst aspect, the reinforcement members (14) may be integrally fixed tothe tubes (12 a) of the core portion (12), so that the heat of the tubes(12 a) can be transmitted to the reinforcement members (14) therefromwithout fail and, as a result, the temperature difference can be madesmaller.

According to a third aspect, in the heat exchanger disclosed in thefirst or second aspect, a heat exchanger is characterized in that thereinforcement members (14) and the tubes (12 a) are independently andrespectively fixed to independent tanks (11, 13).

If the tube (12 a) and the reinforcement member (14) are fixed to thetank (11, 13) in a state they are integrally fixed to each other, thefirst fluid inside the tanks (11, 13) may leak out from the tanks (11,13) at the contacting surface between the surface of the reinforcementmember (14) and the surface of the tube (12 a), etc. Thus, it isdifficult to fix the tubes (12 a) and the reinforcement members (14) tothe tank (11, 13).

In the third aspect, however, as the tubes (12 a) and the reinforcementmembers (14) are fixed to the tanks (11, 13) independently andrespectively, it is possible to fix particularly the reinforcementmembers (14) to the tanks (11, 13) easily. Further, the contactingportions (surfaces) between the surfaces of the reinforcement members(14) and the surfaces of the tubes (12 a) can be eliminated in the tanks(11, 13) and, as a result, it is possible to prevent the first fluidinside the tanks (11, 13) from leaking out therefrom.

According to a fourth aspect, in the heat exchanger disclosed in any oneof the first to the third aspects, the heat exchanger is characterizedin that the reinforcement members (14) are formed in a recess shape thesectional area of which in the direction perpendicular to thelongitudinal direction of the reinforcement members (14) has a bottomportion (14 a) and an opening. In the heat exchanger, on the bottomportion (14 a) of the recess shape a protrusion (14 b) protruding towardan outside of the reinforcement member (14) are formed, and wherein theprotrusion (14 b) and the tube (12 a) are formed so as to come intocontact with each other.

In this configuration, as the reinforcement members (14) having asectional shape which is stronger against bending force and torsionalforce reinforce the core portion (12) together with the tanks (11, 13),the reinforcement ability (the strength of the reinforcement) for thecore portion can be improved.

According to a fifth aspect, in the heat exchanger disclosed in any oneof the first to the fourth aspects, the heat exchanger is characterizedin that in a state in which the protrusion (14 b) and the tube (12 a)are integrally fixed to each other, when viewing from the direction (W)in which the second fluid flows into spaces between the tubes (12 a);and in that the reinforcement member (14) comprises fixing portions (ON)at which the reinforcement member (14) is in contact with the tube (12a) and separated portions (OFF) at which the reinforcement member (14)is separated from the tube (12 a).

In this configuration, when the reinforcement members (14) and the tubes(12 a) are fixed to each other, for example, by brazing or the like, thebrazing material concentrates on the fixing portions (ON) at which thereinforcement member (14) and the tube (12 a) are in contact with eachother and, therefore, the reinforcement member (14) and the tube (12 a)can be more securely fixed to each other.

In addition, as the second fluid can pass through the separated portions(OFF), the heat radiation from the first fluid flowing through the tubes(12 a) integrally fixed to the reinforcement members (14) can beenhanced. Therefore, it is possible to improve the heat exchangingability of the heat exchanger.

According to a sixth aspect, in the heat exchanger disclosed in any oneof the first to the fifth aspects, at least a part of the reinforcementmember (14) may be made of a material larger in an iodization tendencythan that of the tube (12 a). Due to this, portions of the reinforcementmembers (14) formed with a material larger in an iodization tendencythan that of the tubes (12 a) can be corroded earlier than the tubes (12a). As a result, it is possible to prevent from forming pitting holes inthe tubes (12 a) due to corrosion and to prevent the first fluid flowingthrough the tubes (12 a) from leaking out from the tubes (12 a).

According to a seventh aspect, in the heat exchanger disclosed in anyone of the first to the sixth aspects, the reinforcement member (14) maybe attached with a sacrifice (more corrosive) member made of a materiallarger in an iodization tendency than that of the tubes (12 a). As aresult, it is possible to prevent the tubes (12 a) from being corrodeddue to the same reason as in the fifth aspect.

According to an eighth aspect, in the heat exchanger disclosed in anyone of the first to the seventh aspects, the heat exchanger ischaracterized in that the tubes (12 a) have a thickness of 0.3 mm orless.

From reasons such as the weight reduction of the heat exchanger mainbody and the improvement of the heat transmitting coefficient from thetubes (12 a) to the fins (12 b), the plate thickness of tubes (12 a) isreduced so as to provide a thin plate not more than 0.3 mm. If theconstruction of the patent document 1 shown in FIG. 13 is formed byusing the tubes (12 a) with less thickness, the tubes (12 a) areremarkably likely to be damaged due to the heat stress caused by thetemperature difference between the reinforcement members (14) and thetubes (12 a).

In the eighth aspect however, due to the effects of the constructiondescribed in the first to the sixth aspects, the temperature differencebetween the reinforcement members (14) and the tubes (12 a) can be madesmaller and, therefore, it is possible to prevent the tubes (12 a) frombeing damaged even if the plate thickness of the tubes (12 a) is reducedinto a thickness not more than 0.3 mm.

In a ninth aspect of the present invention, according to the heatexchanger in any one of the first to third aspects, the tube (12 a) andthe reinforcement member (14) are in contact with each other in a rangeof more than a half of the length (Lt) along the flowing direction ofthe second fluid in the tube (12 a).

According to this aspect, the contacting area of the reinforcementmember and the tube is increased in comparison with those of theradiator according to the third or the fourth aspect and therefore, theheat of the tubes is transmitted to the reinforcement member withoutfail and it is possible to surely reduce the temperature differencebetween the reinforcement member and the tube. In addition, it ispossible to prevent the tube from being inflated or deformed due to theinternal pressure of the tube, by the reinforcement member.

Moreover, in a case of the heat exchanger of the third or the fourthaspect according to the present invention, the wide area on the surfaceof the tube near the reinforcement member is exposed to the outside.

On the other hand, in the ninth aspect according to the presentinvention the area of the exposed surface of the tube near thereinforcement member is reduced and therefore, the corrosion resistancequality of the tube is advantageously improved.

In a tenth aspect of the present invention, according to the heatexchanger of the ninth aspect, the reinforcement member (14) is formedso that a section of the reinforcement member perpendicular to alongitudinal direction of the reinforcement member (14) becomes a Ushape having a bottom portion (14 a) and an opening portion, and thebottom portion (14 a) is formed to come into contact with the tube (12a).

Due to this, it is possible to effectively transmit heat of the tube tothe wall portion (14 c) of the reinforcement member. In addition, as thereinforcement member having a sectional shape with higher strength withrespect to the bending force and the torsional force reinforces the coreportion together with the tanks it is possible to improve thereinforcement ability for the core portion.

In an eleventh aspect of the present invention, according to the heatexchanger of the tenth aspect, on a bottom portion (14 a) of thereinforcement member (14), holes (14 c) penetrating through the bottomportion (14 a) are formed.

In this configuration, when the reinforcement member and the tube arejoined with each other by brazing, for example, as the holes areprovided on the reinforcement member the brazing material gathers intothe portions in which the reinforcement member and the tube are incontact with each other so that it is possible to fix the reinforcementmember to the tube more securely. In addition, it is possible to checkthe brazing condition through the holes.

The symbols in the parenthesis attached to each means described aboveindicate a correspondence with the specific means in the embodiments tobe described later.

The present invention may be more fully understood from the descriptionof the preferred embodiments of the invention set forth below, togetherwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a plan view showing a first embodiment of the presentinvention in which the present invention is applied to a radiator.

FIG. 2 is a plan view of the radiator according to the first embodimentof the present invention.

FIG. 3 is an enlarged partial view of C portion in FIG. 1.

FIG. 4A is a partial sectional view taken along the line A-A in FIGS. 1and 3.

FIG. 4B is a partial sectional view taken along the line B-B in FIGS. 1and 3.

FIG. 5 is a front view of a portion of a radiator according to a secondembodiment of the present invention which corresponds to C portion inFIG. 1.

FIG. 6 is a plan view of the portion shown in FIG. 5.

FIG. 7 is a partial sectional view taken along the line E-E in FIG. 5.

FIG. 8 is a perspective view of a radiator according to a thirdembodiment of the present invention.

FIG. 9 is an enlarged perspective view of the F portion in FIG. 8.

FIG. 10 is a drawing when viewed from the G arrow direction in FIG. 9.

FIG. 11 is a perspective view of main components of a radiator accordingto a fourth embodiment of the present invention.

FIG. 12 is a perspective view of main components of a radiator accordingto a fifth embodiment of the present invention.

FIG. 13 is a perspective view of a radiator according to patent document1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(First Embodiment)

FIGS. 1 and 2 show a radiator 10 according to a first embodiment of thepresent invention. The radiator 10 which cools a cooling water absorbingheat from a heat source such as an engine, as is generally known, ismounted on a vehicle, so that the radiator is supplied with and iscollided by a cooling air flow blown from a blower (not shown) installedon the upstream side in the air flow. The arrows of the upward and thedownward in the figure indicate the upward direction and the downwarddirection in a state in which it is mounted on the vehicle.

A substantially rectangular prism shaped flow-in side tank is denoted bythe number 11 in the figure and is arranged so that the longitudinaldirection thereof becomes the vertical direction in the arrangement.Naturally, the top surface and the bottom surface of the flow-in sidetank 11 are closed. The flow-in side tank 11 is provided with acylindrical cooling water inlet port 11 a. The cooling water inlet port11 a is connected with a rubber hose (not shown in the figure) throughwhich cooling water flows which has absorbed heat from a heat sourcesuch as an engine and has become high in a temperature.

The flow-in side tank 11 is provided with a plurality of holes (notshown) the number of which corresponds to that of the tubes 12 a. An endof each tube 12 a is inserted into a hole. The other end of the tube 12a is inserted into a hole provided in a flow-out side tank 13 as is theflow-in side tank 11. The flow-out side tank 13 has a substantiallyrectangular prism shape and is arranged so that the longitudinaldirection thereof becomes the vertical direction V in the arrangement.

The tube 12 a has a flat shape which is reduced in a vertical directionthereof and fins 12 b which are formed in a corrugated shape arearranged so as to come into contact with the flat surfaces of the tube12 a. In this configuration, the tubes 12 a and the fins 12 b are in astate of being piled up in layers in a vertical direction V in thefigure. An assembly comprising the tubes 12 a and the fins 12 b arereferred hereinafter as a core portion.

The flow-out side tank 13 is provided with a cylindrical cooling wateroutlet port 13 a. The cooling water outlet port 13 a is connected with arubber hose (not shown in the figure) through which a cooling watercooled as described below re-circulates toward the heat source (anengine).

These components, such as the cooling water inlet port 11 a, the tanks11 and 13, the cooling water outlet port 13 a, the tubes 12 a and thefins 12 b, are made of an aluminum alloy, and are integrally assembledin a unit by brazing, welding or the like.

In the present embodiment, the tubes 12 a are arranged at the ends ofthe core portion 12 in the vertical direction V thereof and, therefore,the tubes 12 a can be fixed on the inserts 14 which are thereinforcement members of the core portion 12. Insertion holes (notshown) in which the parts for securing, such as bolts, are inserted whenthey are used for attaching the radiator 10 to a vehicle are formed onthe inserts 14. Thus the inserts 14 often act as members on which somecomponents are installed, in addition to having roles as reinforcementmembers.

At first, the shape of the insert 14 is explained with reference to FIG.4A. The insert 14 is formed from a plate of thickness about 1.5 to 2 mmby a pressing process so that the sectional area of the insert 14perpendicular to the longitudinal direction of the inserts 14 (the samedirection as the longitudinal direction L of the tubes 12 a) is made ina recess shape having a bottom portion 14 a and an opening. Further, onthe bottom portion 14 a of the insert 14, the insert 14 is provided witha protrusion 14 b protruding toward the outside direction of the insert14 (the downward direction in FIG. 4A). Due to the protrusion 14 b, thesectional area of the insert 14 perpendicular to the longitudinaldirection of the inserts 14 is made in a shape which has steps and thewidth is narrowed to form two steps.

The surface of a plate of the insert 14 which is the side from which theprotrusion 14 b protrudes (the surface on the side contacting the tube12 a) is clad with a material, such as titanium, copper, or the alloythereof, that has an ionization tendency larger than that of an aluminumalloy which makes up the tubes 12 a, etc.

Next, the fixing structure of the insert 14 and the tube 12 a isexplained. The insert 14 and the tube 12 a are integrally fixed by thebrazing, welding or the like as described above, at an area thereofnearer the center of the core portion 12 from voluntary point D (referto FIG. 3 and FIG. 4A) in the longitudinal direction L of the tubes 12a. On the other hand, the insert 14 and the tube 12 a are not integrallyfixed and are separated with each other at an area outside of the coreportion 12 from the point D (refer to FIG. 4B) and are fixed to the tank13 independently with each other in a separated state.

FIG. 3 shows a fixing structure in which the insert 14 is fixed to theflow-out side tank 13 and the tubes 12 a are fixed to the flow-out sidetank 13. The fixing structure in which the inserts 14 are fixed to theflow-in side tank 11 and the tubes 12 a are fixed to the flow-in sidetank 11 are the same.

Next, the operation of the present embodiment in the above configurationis explained. The cooling water of high temperature absorbing heat fromthe heat source such as an engine flows into the flow-in side tank 11from the cooling water inlet port 11 a. The cooling water then isdivided to flow into a plurality of the tubes 12 a from the flow-in sidetank 11 and flows toward the flow-out side tank 13. At this time, theheat of the cooling water flowing through the tubes 12 a is transmittedto the fins 12 b and the air (indicated by the arrow W) flowing throughthe fins 12 b absorbs the transmitted heat. Thus, the cooling waterwhich is cooled and is brought into a low temperature state flows intothe flow-out side tank 13.

The cooling water which flows from the respective tubes 12 a and isgathered into the flow-out side tank 13 returns from the outlet port 13a to the engine (the heat source).

The functions and effects of the first embodiment are listed below.

(1) As the tubes 12 a are arranged on the ends of the core portion 12 inthe vertical direction V thereof and are fixed on the inserts 14 whichare the reinforcement members of the core portion 12, the tubes 12 a canbe prevented from being damaged by thermal stress caused by atemperature difference between the tubes 12 a and the inserts 14.

Due to this construction, compared to the prior art shown in FIG. 8 andhaving a construction in which the inserts 14 and fins 12 b are fixed toeach other, the temperature difference between the tubes 12 a and theinserts 14 can be made smaller. Therefore, heat stress caused by thetemperature difference is unlikely to be produced so that the tubes 12 aare prevented from being damaged by the heat stress.

In addition, the heat of the tubes 12 a integrally fixed to the inserts14 is transmitted to the inserts 14 and therefore, the heat radiationability of the tubes 12 a can be enhanced.

Moreover, compared to the prior art, the number of the tubes 12 a areincreased (to a total two, upper and lower) by fixing the tubes 12 a tothe inserts 14 because the tubes 12 a occupy only a small space.Therefore, the passage area (the total sectional area of the tubes)through which the cooling water flows is increased so that the flowresistance of the cooling water can be reduced.

The conventional fins 12 b integrally fixed with the conventionalinserts 14, that is, the fins 12 b provided on the both ends (the upperend and the lower end) in the piling direction V, has a low heatradiation efficiency because only one side of the fin 12 b is in contactwith the tube 12 a which is the heat source. On the other hand, in thepresent embodiment, as the tubes 12 a are provided on the both ends inthe piling direction V, the both sides of all fins 12 b are in contactwith the tubes 12 a which are the heat source. Therefore, the heatradiation efficiency of the fins 12 b on the both ends (an upper end anda lower end) in the piling direction V can be improved.

These effects can be realized with substantially no change of thedimension of the layers of the tubes 12 a and fins 12 b in the pilingdirection V thereof. Exactly speaking, the dimension of the layers isincreased in the piling direction V by the size of two tubes 12 a butthe size of the tube 12 a in the piling direction V is around a fewmillimeters. In addition, these effects are particularly remarkable inthe case where the thickness of the tube 12 a is reduced to 0.3 mm orless because of a recent tendency in which the weight of the main bodyof a heat exchanger has been reduced, the heat transmitting coefficientfrom the tube 12 a to the fin 21 b has been improved, and the like.

(2) As the respective inserts 14 and the respective tubes 12 a areindependently fixed to the tanks 11 and 13, the inserts 14 and tanks 11,13, and the tubes 12 a and tanks 11, 13 can be fixed without leakage ofthe cooling water.

On the other hand, when the ends of the insert 14 and the tube 12integrally connected to each other are inserted into the holes on thetanks 11 and 13 and the inserted ends are fixed by brazing, welding orthe like, the cooling water in the tanks 11, 13 may leak out therefromat the contacting surface between the surface of the insert 14 and thesurface of the tube 12 a, or the like.

To the contrary, in the present embodiment, the insert 14 and the tube12 a are independently and respectively fixed to the tanks 11 and 13 sothat there is no contacting surface between the surface of the insert 14and the surface of the tube 12 a from which contacting surface thecooling water may leak out. Therefore, the inserts 14 can be easilyfixed to the tanks 11, 13 without a leakage of the cooling water.

(3) The insert 14 is formed in a sectional shape the width of which isnarrowed to form two steps (refer to FIG. 4A), that is stronger againsta bending force and a torsional force, and the protrusion 14 b is fixedto the flat surface of the tube 12 a and, therefore, the reinforcementability of the core portion 12 can be further improved. The expression“stronger against a bending force and a torsional force” has the samemeaning as the expression “the geometric moment of inertia is larger”.

(4) As the protrusion 14 b of the insert 14 contacted with and fixed bythe tube 12 a is clad with a material larger in an ionization tendencythan that of the material making up the tube 12 a, the corrosionresistance of the tube 12 a can be improved.

If the tube 12 a is corroded and forms pitting holes, the cooling waternaturally leaks out therefrom. Because of this, in the presentembodiment, the side surfaces of the protrusion 14 b of the insert 14are clad with a material such as titanium, copper or alloy thereoflarger in an ionization tendency than that of an aluminum alloy makingup the tube 12 a, etc. By this configuration, the clad material largerin an ionization tendency than that of the tubes 12 a is corrodedearlier than the tubes 12 a and therefore, the tubes 12 a are preventedfrom being corroded, in other words, the anti-corrosive ability of thetubes 12 a can be improved.

(Second Embodiment)

A radiator according to a second embodiment has substantially the sameconfiguration as that of the first embodiment but the shape of theinserts 14 is different from that of the first embodiment. The inserts14 of the first embodiment have a constant sectional shape (refer toFIG. 4A) at the positions nearer to the center side of the core portionthan D point in FIG. 3.

On the other hand, the inserts 14 of the present invention when viewingthem from the direction from which the cooling air flows into the coreportion (that is, the vertical direction on the paper of FIG. 5), areformed to have fixing portions (corresponding to ON portions in FIGS. 5and 6) in which the insert 14 and a tube 12 a are in contact with andfixed to each other and separated portions (corresponding to OFF portionin FIGS. 5 and 6) in which the insert 14 and the tube 12 a are separatedfrom each other.

At the fixing portions ON, the insert 14 has a sectional shape the widthof which is narrowed to form two steps, as shown in FIG. 4A and, on theother hand, at the separated portions OFF the insert 14 has a sectionalshape like a recess as shown in FIG. 7. The fixing portions ON and theseparated portions OFF are alternately provided in the longitudinaldirection L of the tubes 12 a.

According to this construction, in a case where the insert 14 and thetube 12 a are fixed to each other, for example, by brazing, as a brazingmaterial is collected in the fixing portions ON where the insert 14 andthe tube 12 a are in contact with each other, the insert 14 and the tube12 a can be more securely fixed to each other.

Moreover, as the cooling air can pass through the separated portions OFFthe heat can be promoted to be radiated from the cooling water flowingthrough the tube 12 a integrally fixed with the insert 14. Therefore,the radiation ability of the radiator can be enhanced.

This embodiment can perform the same functions and effects (1) to (4) asdescribed in the first embodiment.

(Third Embodiment)

A third embodiment of the present invention will be explained below.FIG. 8 shows a perspective view of a radiator according to the thirdembodiment of the present invention, FIG. 9 shows an enlargedperspective view of F portion in FIG. 8, and FIG. 10 shows a drawingwhen viewed in the G arrow direction in FIG. 9. In those figures, partsof this embodiment, the same as or equivalent to those of the firstembodiment, are denoted with the same symbols attached thereto and theseparts are not explained here.

In each embodiment described above, the cooling water inlet port 11 a,the tanks 11 and 13, the cooling water outlet port 13 a, the tubes 12 aand the fins 12 b are made of an aluminum alloy, however in the presentembodiment, parts of the tanks 11, 13, the cooling water inlet port 11a, and the cooling water outlet port 13 a are made of a resin, such as anylon or the like.

As shown in FIGS. 8 and 9, a flow-in side tank 11 for cooling watercomprises a tank body 111 having a substantially rectangular columnarshape with an open portion at one of the faces thereof, and aplate-shaped core plate 112 closing the open portion of the tank body111. The tank body 111 is made of a resin and is integrally formed withthe cooling water inlet port 11 a. The core plate 112 is made of analuminum alloy.

The tank body 111 and the core plate 112 are integrated with each otherby calking the outer peripheries of the core plate 112. An O-ring (notshown in the figures) for sealing is installed between the tank body 111and the core plate 112.

The holes (not shown in the figures) into which the tubes 12 a areinserted are formed on the core plate 112 and one end of the tube 12 ais inserted into the hole. A protruding piece 112 a which fixes theinsert 14 by calking is formed on the core plate 112.

The flow-out side tank 13 for cooling water has a similar configurationas that of the flow-in side tank 11 and comprises a tank body 131, acore plate 132 and an O-ring (not shown in the figures), and protrudingpieces 132 a are formed on the core plate 132.

The inserts 14 which are made by pressing a plate material made of analuminum alloy and a section perpendicular to the longitudinal directionof the insert 14 (the same direction as the longitudinal direction L ofthe tubes 12 a) as shown in FIG. 10 is formed so that it becomes a Ushape having a flat bottom portion 14 a and an opening portion.

The length Li of the insert 14 along the air flowing direction is madesubstantially equal to the length Lt of the tube 12 a along the airflowing direction and thereby, the contacting area of the insert 14 andthe tube 12 a is maintained sufficiently by joining the bottom portion14 a of the insert 14 to the flat surface of the tube 12 a by brazing,welding or the like.

The bottom portion 14 a of the insert 14 and the flat surface of thetube 12 a are in contact with each other in a range more than a half ofthe length Lt of the tube 12 a, in the air flowing direction, anddesirably in a range more than two third of the length Lt.

As shown in FIG. 8 and FIG. 9, on the bottom portion 14 a holes 14 c areformed which penetrate through the bottom portion 14 a. A number of theholes 14 c having an oval shape the long side of which is parallel tothe longitudinal direction of the insert 14 are arranged along thelongitudinal direction of the insert 14.

Installation pieces 14 d which extend from the bottom portion 14 a andare bent in a L shape are formed on the both ends in the longitudinaldirection of the insert 14. In detail, the installation piece 14 dextend toward the tank 11 or 13 and in a state parallel to thelongitudinal direction L of the tube 12 a after extending toward theopposite side of the tube 12 a (the outside of the lamination directionof the tubes) from the bottom portion 14 a.

The installation pieces 14 d are held in a sandwiched state between themain body of the core plate 112, 132 and the protruding piece 112 a, 132a by calking the protruding piece 112 a, 132 a of the core plate 112,132.

According to the present embodiment, the parts of the tanks 11, 13, thecooling water inlet port 11 a and the cooling water outlet port 13 a aremade of a resin and therefore, the weight of the radiator can be reducedand the cost thereof can be reduced.

As the bottom portion 14 a of the insert 14 and the flat surface of thetube 12 a are made to come into contact with each other in a range ofmore than a half of the length Lt of the tube 12 a along the air flowingdirection, the contact area of the insert 14 and the tube 12 a in thisembodiment is increased in comparison with those of the radiatorsaccording to the first and the second embodiments and therefore the heatof the tubes 12 a is transmitted to the insert 14 without fail and it ispossible to surely reduce the temperature difference between the insert14 and the tube 12 a.

In addition, it is possible to prevent the tubes 12 a from beinginflated or deformed due to the internal pressure of the tubes, by usingthe insert 14.

The area of the exposed surface of the tube 12 a at the insert 14 sideis reduced in comparison with those of the radiators according to thefirst and the second embodiments and therefore, the corrosion resistanceof the tubes 12 a is advantageously improved.

As the insert 14 which has a sectional shape with higher strength withrespect to the bending force and the torsional force reinforces the coreportion 12 together with the tanks 11, 13, it is possible to improve thereinforcement performance of the core portion 12.

When the insert 14 and the tube 12 a are joined with each other bybrazing as the holes 14 a are provided on the insert 14 the brazingmaterial gathers into the portions in which the insert 14 and the tube12 a are in contact with each other (in which there is no hole 14 a) itis possible to fix the insert 14 to the tube 12 a more surely. Inaddition, it is possible to check the brazing condition through theholes 14 c.

As the insert 14 and the tube 12 a are independently fixed to the tanks11, 13 respectively, it is possible to join the insert 14 and the tubes12 a with the tanks 11, 13 without leakage of the cooling water.

(Fourth Embodiment)

A fourth embodiment of the present invention will be explained below.FIG. 11 shows a perspective view of main components (corresponding tothe F portion in FIG. 8) of a radiator according to the fourthembodiment of the present invention. In the figures, the parts of theembodiment same as or equivalent to those of the third embodiment aredenoted with the same symbols attached thereto and these parts are notexplained here.

As shown in FIG. 11, installation pieces 14 d extending from the bottomportion 14 a are provided on the both ends in the longitudinal directionof the insert 14. More specifically, the installation piece 14 d extendsin an oblique direction from the bottom portion 14 a toward the tank 11or 13 and at the opposite side of the tube 12 a (to the outside in thelamination direction V of the tubes).

On the core plate 112 holes (not shown in the figure) into which theinstallation pieces 14 d are inserted are formed and the ends of theinstallation pieces 14 d are inserted into the holes.

The holes into which the installation pieces 14 d are inserted areindependently provided and separated from the holes into which the tubes12 a are inserted. Though not shown in the figure, the holes (not shownin the figure) into which the installation pieces 14 d are inserted areformed on the core plate 132 of the flow-out side tank 13 and the endsof the installation pieces 14 d are inserted into the holes.

According to this embodiment, the insert 14 and the tube 12 a areindependently fixed to the tanks 11, 13 respectively, so that it ispossible to join the insert 14 and the tube 12 a with the tanks 11, 13without the leakage of cooling water.

(Fifth Embodiment)

A fifth embodiment of the present invention will be explained below.FIG. 12 shows a perspective view of main components (portionscorresponding to the F portion in FIG. 8) of a radiator according to thefourth embodiment of the present invention. In the figures, the parts ofthe embodiment same as or equivalent to those of the third and fourthembodiments are denoted with the same symbols attached thereto and theseparts are not explained here.

Though in the fourth embodiment, the insert 14 and the tube 12 a areindependently fixed to the holes formed on the core plate 112, 132respectively, as shown in FIG. 12, the end of the insert 14 and the endof the tube 12 a both may be inserted into one hole formed on the coreplate 112, 132 so as to be fixed to the hole by brazing, welding or thelike.

(Other Embodiments)

In the embodiments described above, the radiator 10 in which the coolingwater absorbing heat from a heat source is made to radiate heat are usedas an example of the heat exchanger, but the heat exchanger may be acondenser in which a gas-phase refrigerant is condensed into aliquid-phase refrigerant by heat exchanging in the heat exchanger.Further, the effects of the present invention can be naturally realizedin a heat exchanger in which a liquid-phase refrigerant is evaporatedinto a gas-phase refrigerant by the heat exchanging in the heatexchanger, that is, an evaporator.

In the above-mentioned embodiments, the examples in which the inserts 14and the tubes 12 a are fixed to each other by brazing, welding, or thelike are shown but the effects of the present invention can be performedeven in a case where the inserts 14 and the tubes 12 a come into contactwith each other.

In the above-mentioned embodiments, the examples in which the tanks 11and 13 are arranged at the both ends of the tubes 12 a are shown but aconfiguration in which the tubes are formed in a U shape and the fluidflows out from and into one tank may be applied. In this case, theinside space of the tank is necessarily separated into a flow-out spaceand a flow-in space.

In the above-mentioned embodiments, an example in which the fixingsurfaces (the protrusions 14 b) at which the insert 14 and the tube 12 aare fixed to each other are clad with a material larger in an ionizationtendency than that of the tubes 12 a are shown but on the reverse sideof the tube 12 a, that is, on the bottom surface 14 a side of the insert14 a material may be clad. Alternatively, an independent part (forexample, a plate material) which is made of a material larger in anionization tendency may be integrally fixed to the insert 14.

Further alternatively, the insert 14 itself may be made of a materiallarger in an ionization tendency. The basic material making up theinsert 14 may be added with a material larger in an ionization tendencyby a specific ratio with respect to the basic material, thereby making apart including the material having larger ionization tendency by ahigher ratio (more rich) corrode first.

Though in the third to the fifth embodiment, the holes 14 c are formedon the bottom portion 14 a of the insert 14, the holes 14 c may not beformed on the bottom portion 14 a of the insert 14. In this case, thecontacting area of the insert 14 and the tube 12 a is further increased.

While the invention has been described by reference to specificembodiments chosen for the purposes of illustration, it should beapparent that numerous modifications could be made thereto, by thoseskilled in the art, without departing from the basic concept and scopeof the invention.

1. A heat exchanger comprising: a core portion having a plurality oftubes through which a first fluid flows and which are arrange so as tobe laid in layers, and fins arranged between a plurality of the tubesand for promoting heat exchanging between the first fluid and a secondfluid flowing through a space between the tubes; and tanks arranged atends of the tubes and communicating with a plurality of the tubes; andreinforcement members fixed to the tanks and for reinforcing peripheriesof the core portion as well as the tanks; wherein the reinforcementmembers and the tubes of a plurality of the tubes arranged at theoutermost ends in a piling direction of the tubes are arrange so thatthe tube and the reinforcement member come into contact with each other.2. The heat exchanger as set forth in claim 1, wherein the reinforcementmembers are integrally fixed to the tubes of the core portion.
 3. Theheat exchanger as set forth in claim 1, wherein the reinforcementmembers and the tubes are independently and respectively fixed to thetanks.
 4. The heat exchanger as set forth in claim 1; wherein thereinforcement members are formed in a recess shape a sectional area ofwhich in a direction perpendicular to a longitudinal direction of thereinforcement members has a bottom portion and an opening; wherein onthe bottom portion of the recess shape a protrusion protruding toward anoutside of the reinforcement member is formed; and wherein theprotrusion and the tube are formed so as to come into contact with eachother.
 5. The heat exchanger as set forth in claim 1; wherein in a statein which the reinforcement member and the tube are integrally fixed toeach other, when viewing from a direction in which the second fluidflows into spaces between the tubes, the reinforcement member is formedto have fixing portions at which the reinforcement member is in contactwith the tube and separated portions at which the reinforcement memberis separated from the tube.
 6. The heat exchanger as set forth in claim1, wherein at least a part of the reinforcement member is made of amaterial larger in an iodization tendency than that of the tubes.
 7. Theheat exchanger as set forth in claim 1, wherein the reinforcement memberis attached with a sacrificial member made of a material larger in aniodization tendency than that of the tubes.
 8. The heat exchanger as setforth in claim 1, wherein the tubes have a thickness of 0.3 mm or less.9. The heat exchanger as set forth in claim 1, wherein the tube and thereinforcement member are in contact with each other in a range of morethan half the length in a flowing direction of the second fluid in thetube.
 10. The heat exchanger as set forth in claim 9, wherein thereinforcement member is formed so that a section of the reinforcementmember perpendicular to a longitudinal direction of the reinforcementmember becomes a U shape having a bottom portion and an opening portionand the bottom portion is formed to come into contact with the tube. 11.The heat exchanger as set forth in claim 10 wherein, on a bottom portionof the reinforcement member, holes penetrating through the bottomportion are formed.